The present invention relates to an incinerator for burning combustible material such as municipal trash or waste.
Generally, when waste is burned in an incinerator, it is fed into one end of an elongated cylinder rotary furnace defining a combustion chamber, and an air flow is directed over the waste into the interior of the rotary furnace to support the combustion. Combustion exhaust gas and ashes are removed from the other end of the furnace. However, the waste is often not sufficiently mixed with the combustion air flow to create complete burning so that a considerable amount of residual waste remains after incineration.
A high volume of air flow is typically directed into the furnace in an attempt to improve the completeness of combustion, substantially raising furnace temperatures to excessive levels.
If the temperature of the furnace is elevated, the service life of the furnace components is reduced. To overcome this problem, a water cooling wall is provided around a periphery of the rotary furnace and a number of openings are formed therein to define a boiler space, creating an integrated boiler and furnace. With this structure, the combustion air flow can be introduced from the furnace bottom to improve combustion. However, a boiler-integrated furnace is expensive.
Conventional waste incinerators have another problem: since the temperature of the furnace reaches very high levels, a harmful gas (NOx) is generated by combustion in the furnace. To eliminate this problem, a reduction apparatus may be provided on a gas discharge duct. However, this makes the incineration system complicated and expensive.
Therefore, an object of the present invention is to provide an incinerator which does not have a boiler, but can supply an air flow in a desired manner and prevent the furnace from reaching excessive temperatures.